This invention relates to an aircraft helmet assembly adapted to support a portable visual display unit in a predetermined position relative to the eye of the pilot.
Recently developed target display systems for pilots of helicopters or other aircraft include a cathode ray tube (CRT) which is mounted directly on the hard outer shell of the pilot's helmet at a position, for example, directly below the right ear. An optical system integral with the CRT and comprising one or more reflectors allows the pilot to view the image while looking generally ahead. Because of the fairly long path length of the optical system of the CRT display, it is extremely important that the system be maintained in an accurately aligned position relative to the eye of the pilot. In one specific system, for example, it is desirable to maintain the distance from the center of the eye to the edge of the helmet shell between 17/8 and 21/8 inches. Owing to variations in individual head size and configuration, however, it is difficult to maintain this tolerance with any degree of reliability. Further, the fore-and-aft wobbling of existing helmet shells, while small, is sufficient to cause misalignment even if the shell edge is initially properly aligned.